1. Technical Field
The invention relates to a display panel and a display device and, in particular, to a display panel and a display device formed by the polymer sustained alignment (PSA) technology.
2. Related Art
With the progress of technologies, display devices have been widely applied to various kinds of fields. Especially, liquid crystal display (LCD) devices, having advantages such as compact structure, low power consumption, less weight and less radiation, gradually take the place of cathode ray tube (CRT) display devices, and are widely applied to various electronic products, such as mobile phones, portable multimedia devices, notebooks, LCD TVs and LCD screens.
In the multi-domain vertical alignment (MVA) technology for enhancing the thin film transistor (TFT) liquid crystal display (LCD), the PSA (polymer sustained alignment) is a maturely developed technique to increase the aperture ratio and contrast. In the PSA technology, a photosensitive monomer is added into the LC layer and/or the alignment layer and then illuminated by the ultraviolet under the application of an electric field, and therefore the photosensitive monomer is polymerized to become a polymer on the alignment layer. Besides, the polymer arranges according to the pattern of a patterned transparent conductive layer of the TFT substrate or CF substrate, and therefore the multi-domain alignment of the LC can be achieved by the polymer.
In the conventional PSA technology, a patterned notch is formed on the transparent conductive layer of the TFT substrate or the CF substrate. When the pixel electrode of the display panel is driven to generate an electric field, the LC can rotate along the pre-tilted direction through the notch and the alignment layer formed on the transparent conductive layer. Therefore, the response of the LC can be accelerated, and besides, the multi-domain alignment of the display panel can be achieved.
However, when the pixel electrode of the display panel is driven to generate the electric field, the electric-field intensity of the notch is weaker than other regions having the transparent conductive layer, because the transparent conductive layer is not disposed in the notch. Accordingly, the LC molecules in the notch will be affected by the surrounding electric field and the rotation thereof thus becomes uncontrollable. Therefore, the unstable rotation of the LC molecules will affect the response time of the LC molecules and also result in the problem of image retention.
Therefore, it is an important subject to provide a display panel and a display device where the unstable rotation situation of the LC molecules is diminished so that the response ability of the LC in the notch can be maintained and the image retention can be avoided.